Asking Elder’s Bane players about the Collector

I’m close to becoming Elder’s Bane and have only 5.2.5 and 5.2.6 left to 100%. It was a while back I defeated the collector and I think I used about 300 units on him then. So I’m curious to ask The elders bane community what they did: how many revives/units did you use on 100%ing him? I need to stockpile as I’d rather not spend any cash.